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Abstract:

The invention provides a method for producing titanium tetrachloride by
using a low grade titanium material, and belongs to the chemical field.
The technical problem to be solved is to provide a method for producing
titanium tetrachloride by using a low grade titanium material capable of
continuous industrialized production. The method is characterized in that
the low grade titanium material containing a certain proportion of
titanium carbide is caused to directly react with chlorine at
600-700° to produce the titanium tetrachloride. Long-time
continuous and stable operation can be realized by using the process
parameters of the method, and chlorination rate of the titanium carbide
in the titanium material reaches above 90%, so that the titanium material
can be better used for producing the titanium tetrachloride.

Claims:

1-6. (canceled)

7. The method for producing titanium tetrachloride by using a low grade
titanium material, said method comprising the following steps: a. adding
the low grade titanium material to a furnace, and heating to start up the
furnace; b. continuing adding the low grade titanium material when the
furnace is heated to a temperature of 420.+-.40.degree. C., and
introducing chlorine with a volume concentration of 75%-85% for reaction
based on a reaction rate according to a TiC content of the low grade
titanium material; c. controlling the temperature of the furnace at
610-650.degree. C. as the temperature in the furnace rises slowly after
the reaction starts; d. collecting titanium tetrachloride-containing gas
generated during the reaction for condensation treatment to obtain liquid
titanium tetrachloride and tail gas, and separating out reacted inert
chloride residue based on a volume of the low grade titanium material
added; and e. treating and discharging a remaining residue after the
reaction.

8. The method for producing titanium tetrachloride by using a low grade
titanium material of claim 7, wherein the low grade titanium material in
step a contains 6%-16% of titanium carbide.

9. The method for producing titanium tetrachloride by using a low grade
titanium material of claim 8, wherein the low grade titanium material in
step a contains 7%-12% of titanium carbide.

10. The method for producing titanium tetrachloride by using a low grade
titanium material of claim 7, wherein hot air heated by natural gas or
kerosene is used to heat the low grade titanium material in the furnace
to start up the furnace in step a.

11-12. (canceled)

13. The method for producing titanium tetrachloride by using a low grade
titanium material of claim 7, wherein the reaction temperature in step c
is controlled by taking part of the inert chloride residue generated in
the reaction out of a system for cooling and returning to the system.

14. The method for producing titanium tetrachloride by using a low grade
titanium material of claim 7, wherein the reaction temperature in step c
is controlled by transferring the low grade titanium material from the
furnace to an external catalyst cooler for circulating cooling.

Description:

FIELD OF THE INVENTION

[0001] The invention belongs to the chemical field, and relates to a
method for producing titanium tetrachloride, in particular to a method
for producing titanium tetrachloride by using a low grade titanium
material.

DESCRIPTION OF THE RELATED ART

[0002] With the rapid development of the global titanium industry,
titanium ore resource has become one of the key factors that restrict the
titanium industry. As high grade titanium ore resources were greatly
exploited in the early days of the titanium industry, the high grade
titanium ore resources are getting less and less, and such high grade
titanium ore resources are characterized by concentrated production
places and monopolized by a small number of large groups, while low grade
titanium ore resources are characterized by wide distribution,
diversified occurrences and great reserves. Therefore, developing the
chlorination process for the low grade titanium materials can solve the
present problem of resource shortage, widely promote their application,
comprehensively improve the worldwide titanium industry and increase the
yield of relevant products.

[0003] Chinese Patent Application 200610021468.4 "Method for extracting
iron, titanium and vanadium from high titanium-bearing ferro-vanadium
concentrate" discloses a chlorination process of carbide slag of
vanadium-titanium chromium, however, the process is involved with the
high titanium-bearing ferro-vanadium concentrate and is incapable of
achieving large-scale continuous industrial production.

[0004] Chinese Patent ZL87107488.5 "Method for preparing titanium
tetrachloride by using titanium-bearing blast furnace slag" discloses a
process for preparing titanium tetrachloride by using titanium-bearing
blast furnace slag containing 15-30% of titanium dioxide. The process
comprises the following main steps: carbonizing the titanium-bearing
blast furnace slag at 1600-1800°, and preparing the titanium
tetrachloride by chlorination in a fluidized bed at 250-600°,
preferably 400-550°. The process is unavailable for treating raw
materials with lower titanium dioxide content, and the application
thereof also considers that the fluidized bed can not produce any product
at temperatures over 600°.

[0005] Generally, the low grade titanium material refers to the high
titanium-bearing blast furnace slag generated in producing common
titanium products, or other low grade titanium materials with TiO2
content lower than 25% in general, and shall be subject to high
temperature carbonization at 1800-2000° before use. Other relevant
technical report on producing the titanium tetrachloride by chlorination
of the low grade titanium ores is not available at present.

[0006] At present, it is required to develop methods for producing the
titanium tetrachloride by using the low grade titanium materials capable
of continuous industrial production with simpler process at lower cost in
the field.

SUMMARY OF THE INVENTION

[0007] The technical problem to be solved in the invention is to provide a
method for producing titanium tetrachloride by using a low grade titanium
material capable of continuous industrial production. The technical
proposal of the method is to cause the low grade titanium material to
directly react with chlorine at 600-700° to produce the titanium
tetrachloride.

[0010] The reaction temperature at which the low grade titanium material
directly reacts with the chlorine is preferably 610-650°, more
preferably 640±10°.

[0011] The volume concentration of the chlorine in the method is 50%-100%,
preferably 75%-85%.

[0012] The method comprises the following steps:

a. adding the low grade titanium material to a furnace, and heating to
start up the furnace; b. adding the remaining low grade titanium material
when the furnace is heated to 420±40°, and introducing chlorine
with the volume concentration of 50%-100% for reaction based on reaction
rate according to TiC content of the low grade titanium material; c.
controlling temperature of the furnace at 600-700° as the
temperature in the furnace rises slowly after the reaction starts; d.
collecting titanium tetrachloride-containing gas generated during
reaction for condensation treatment to obtain liquid titanium
tetrachloride and tail gas, and taking out reacted inert chloride residue
based on the volume of the material added; and e. treating and
discharging the remaining residue after the reaction.

[0013] The low grade titanium material in step a of the method contains
6%-16% of titanium carbide, and further contains 7%-12% of titanium
carbide.

[0014] Hot air heated by natural gas or kerosene is used in step a of the
method to heat the material in the furnace to start up the furnace.

[0015] The reaction temperature at which the low grade titanium material
directly reacts with the chlorine in step b of the method is controlled
at 610-650°, preferably 640±10°.

[0016] The volume concentration of the chlorine in step c of the method is
preferably 75%-85%. The temperature is controlled by taking part of inert
chloride residue generated in the reaction out of a system for cooling
and returning to the system in step c of the method, or controlled by
transferring the material from the reaction furnace to an external
catalyst cooler for circulating cooling. Of course, the above two method
can be used at the same time.

[0017] The method for producing titanium tetrachloride by using a low
grade titanium material has the advantages of being very convenient as
the low grade titanium material can be caused to directly react with the
chlorine at 600-700° to produce the titanium tetrachloride. The
method of the invention can enable long-time continuous and stable
operation and industrialization, and chlorination rate of titanium
carbide in the titanium material can reach above 90%. Meanwhile, the
method does not need porous reduction media such as porous carbon, thus
greatly saving the cost.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is schematic diagram of the method for producing titanium
tetrachloride by using a low grade titanium material of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The invention is described in detail with reference to the
following example, but is not to be limited thereto.

[0020] The low grade titanium material of the invention is from high
titanium-bearing blast furnace slag or other low grade titanium materials
(TiO2 content is lower than 25%), and formed by carbonization at the
high temperature of 1800-2000°. Generally, the low grade titanium
material used in the invention contains 6%-16% of titanium carbide, and
total titanium content (total content of titanium element in raw
material, and titanium element may exist in titanium carbide, titanium
dioxide, titanium trioxide, titanium nitride, etc.) is 4.8%-14%.

[0021] In the reaction, hot air from combustion of natural gas or kerosene
is used to heat the material in the furnace to start up the furnace, and
1/3 of the material for the normal reaction is added to the furnace when
the furnace is started up. Generally, the material is a 1:1 mixture of
the low grade titanium-containing titanium carbide material to be treated
and chloride residue generated during previous implementation of the
process. Hot air can be changed into reaction gas at any time for
reaction after the temperature in the furnace reaches 400°. The
reaction gas is generally a mixture of chlorine and air, and the volume
concentration of the chlorine is 50%-100%, preferably 75%-85%. The
reaction gas also can be mixture of chlorine and other inert gas such as
nitrogen and argon instead of air.

[0022] As chlorination reaction of the titanium carbide gives off a lot of
heat during the reaction, the system temperature can not be controlled in
a reasonable range if the heat is not removed in time. Therefore, the
heat of the reaction system needs to be removed by a reasonable method.
The method of the invention can take part of inert chloride residue
generated in the reaction out of the system for cooling and returning the
chloride residue to the system, thus diluting reaction heat and
controlling the temperature of the reaction system. Meanwhile, the system
temperature can be controlled by transferring the material from the
furnace to an external catalyst cooler for circulating cooling. The two
methods can be separately or jointly used accordingly. The reaction
temperature is controlled at 600-700° during chlorination,
preferably 610-650°, more preferably 640±10°.

[0023] The invention can be applied to boiling chlorination furnaces with
diameter ranging from 50 mm to 10000 mm or even larger boiling
chlorination furnaces by controlling residence time of solid materials in
the furnaces and mean flow rate of gas in beds. The residence time of the
solid materials is controlled at 28-60 min and the mean flow rate of gas
is controlled at 0.05-0.5 m/s according to productivity requirements in
specific production.

[0024] During the reaction, titanium tetrachloride-containing tail gas
enters dust collection and condensation systems from the top of the
chlorination furnace, fine granular furnace burden carried over by the
tail gas is collected by the dust collection system, and titanium
tetrachloride gas is cooled below boiling point in the condensation
system, form liquid and is collected in a special storage tank. The tail
gas enters a tail gas treatment system after condensation, and acid gas
is vented after washing by alkali liquor. Meanwhile, the residue that is
discharged from the reaction furnace and is not returned to the system
enter a residue treatment system, and can be used as a raw material for
producing cement after purification treatment according to the existing
treatment methods.

[0025] The low grade titanium material used in the examples of the
invention is from carbide slag of blast furnace slag formed by
carbonization of the high titanium-bearing blast furnace slag at high
temperature, and typical components of the low grade titanium material
are as shown in Table 1.

[0026] Carbide slag of blast furnace slag (see Table 1 for typical
components) and chlorine were used as reaction raw materials, and
diameter of the furnace body was 200 mm.

[0027] Totally 20 kg of fresh carbide slag and chloride residue were added
at 1:1 ratio to the chlorination furnace and heated. Chlorine and air
were introduced at a ratio of 75% when the temperature of the materials
in the furnace reached 400°, that is, chlorine charging rate was 6
m3/h, dry air charging rate was 2 m3/h, fresh material feeding
rate was 30 kg/h, and residue returning rate was 10 kg/h. The residence
time of the solid materials was 40 min, the temperature was controlled at
640±10°, and the system stably operated for over 8 h. The
chlorination rate of the titanium carbide in the raw materials was 91%,
and coarse titanium tetrachloride collected by the condensation system
was 76 kg.

Example 2

Preparation of Titanium Tetrachloride by the Method of the Invention

[0028] Carbide slag of blast furnace slag (see Table 1 for typical
components) and chlorine were used as reaction raw materials, and
diameter of the furnace body was 200 mm.

[0029] Totally 20 kg of fresh carbide slag and chloride residue were added
at 1:1 ratio to the chlorination furnace and heated. Chlorine and air
were introduced at a ratio of 50% when the temperature of the materials
in the furnace reached 400°, that is, chlorine charging rate was 4
m3/h, dry air charging rate wais 4 m3/h, fresh material feeding
rate was 25 kg/h, and residue returning rate was 15 kg/h. The residence
time of the solid materials was 28 min, the temperature was controlled at
610±10°, and the system stably operated for over 8 h. The
chlorination rate of the titanium carbide in the raw materials was 86%,
and coarse titanium tetrachloride collected by the condensation system
was 63 kg.

Example 3

Preparation of Titanium Tetrachloride by the Method of the Invention

[0030] Carbide slag of blast furnace slag (see Table 1 for typical
components) and chlorine were used as reaction raw materials, and
diameter of the furnace body was 200 mm.

[0031] Totally 20 kg of fresh carbide slags and chloride residue were
added at 1:1 ratio to the chlorination furnace and heated. Pure chlorine
was introduced at 6 m3/h when the temperature of the materials in
the furnace reached 400°. Fresh material feeding rate was 35 kg/h,
and residue returning rate was 5 kg/h. The residence time of the solid
materials was 42 min, the temperature was controlled at
610±10°, and the system stably operated for over 8 h. The
chlorination rate of the titanium carbide in the raw materials was 84%,
and coarse titanium tetrachloride collected by the condensation system
was 88 kg.

Example 4

Preparation of Titanium Tetrachloride by the Method of the Invention

[0032] Carbide slag of blast furnace slag (see Table 1 for typical
components) and chlorine were used as reaction raw materials, and
diameter of the furnace body was 200 mm.

[0033] Totally 2000 kg of fresh carbide slags and chloride residue were
added at 1:1 ratio to the chlorination furnace and heated. Chlorine and
air were introduced at a ratio of 78% when the temperature of the
materials in the furnace reached 400°, that is, chlorine charging
rate was 430 m3/h, dry air charging rate was 186 m3/h, fresh
material feeding rate was 4000 kg/h, and residue returning rate was 800
kg/h, and the residence time of the solid materials was 45 min.
Meanwhile, an external catalyst cooler was used to cause materials in the
furnace to circulate therein for heat exchange with circulating water in
coils of the external catalyst cooler. The reaction temperature in the
furnace was controlled at 630±10°, and the system stably
operated for over 72 h. The chlorination rate of the titanium carbide in
the raw materials was 90%, and coarse titanium tetrachloride collected by
the condensation system was 120 t.